I am so sorry for the loss of your precious Katie. Sounds as though she had a good long life with you, you were blessed.
Have you or would you consider a rescue yorkie? If so, Oklahoma is represented by a couple of different yorkie rescue groups, OK Yorkie Rescue out of the OKC area, and then I have two foster girls for Yorkie Haven Rescue.
If rescue isn't for you right now, then I would contact someone with the Yorkshire Terrier Club of Oklahoma City (Ken Lambert). Oklahoma does have several reputable breeders, you just have to be careful and do your homework, as you are trying to do. Good Luck!
American Kennel Club - Yorkshire Terrier Club of Oklahoma City - OKLAHOMA CITY - OK - 2814